Along with pursuing downsizing, multifunctionalization, increasing communication speeds, and the like of electronic equipment, further densification of the circuit board used in electronic equipment is required, and multilayering of circuit boards is being achieved to meet the requirements of densification. The multilayer circuit board is formed, for example, on an inner layer substrate made of an electrical insulating layer and a conductor layer formed on a surface of the electrical insulating layer, by laminating an electrical insulating layer and forming a conductor layer on the electrical insulating layer, and further repeating laminating the electrical insulating layers and forming the conductor layers.
As a method of manufacturing the laminate body for forming the multilayer circuit board, for example, Patent Document 1 discloses a manufacturing method of a multilayer printed wiring board that requires a step of heating and applying pressure to perform laminating under vacuum conditions, in a condition of directly covering a resin composition layer of an adhesive film onto at least a pattern processed portion of one surface or both surfaces on a supporting base film having a release layer and a circuit board that was pattern processed thereof, a step of thermally curing the resin composition in a condition attached to the supporting base film, a step of hole punching by a laser or drill, a step of peeling the supporting base film, a step of performing roughening treatment to a resin composition surface, and then a step of plating the roughened surface to form a conductor layer.
In the Patent Literature 1, the resin composition is thermally cured in a condition attached to a supporting body such as a supporting base film, and thereby, foreign matter that attaches during thermal curing of the resin composition and defects such as disconnecting, shorting, and the like caused by the foreign matter are prevented. Furthermore, in Patent Literature 1, after the resin composition in the condition attached with the supporting body is thermally cured, and before the supporting body is peeled, a small diameter via hole can be formed by performing hole punching by a laser or drill.